Numerical study of the influence of turbulence-chemistry interaction in URANS simulations of diesel spray flame structures under marine engine-like conditions

The present work performs Unsteady Reynolds-averaged Navier-Stokes simulations to study the effect of turbulence-chemistry interaction (TCI) on diesel spray flames. Three nozzle diameters (𝑑0) of 100 μm, 180 μm, and 363 μm are considered in the present study. The Eulerian Stochastic Fields (ESF) method (with TCI effect) and Well-Stirred Reactor (WSR) model (without TCI effect) are considered in the present work. The model evaluation is carried out for ambient gas densities ( ) of 30.0 kg/m 𝜌𝑎𝑚 3 and 58.5 kg/m3. ESF method is demonstrated to be able to reproduce the ignition delay time (IDT), and lift-off length (LOL) with an improved accuracy than that from the WSR method. Furthermore, TCI has relatively more influence on LOL than on IDT. A normalized LOL (LOL*) is introduced, which considers the effect of 𝑑0, and its subsequent effect on the fuel-richness in the rich premixed core region is analyzed. The RO2 distribution is less influenced by the TCI effect as ambient density increases. The ESF model generally predicts longer and wider CH2O distribution. The difference in the spatial distribution of CH2O between the ESF and WSR model diminishes as 𝑑0 increases. At 𝜌𝑎𝑚 = 30.0 kg/m3, the ESF method results in a broader region of OH with a lower peak OH values than in the WSR case. However, at 𝜌𝑎𝑚 = 58.5 kg/m3, the variation of peak OH value is less susceptible to the increase in 𝑑0 and the presence of TCI model. Furthermore, the influence of the TCI on the total OH mass decreases as 𝑑0 increases. The total NOx mass qualitatively follows the same trend as the total OH mass. This present work clearly shows that influence of TCI on the global spray and combustion characteristics becomes less prominent when 𝑑0 increases.